i386: Rename ELF_MACHINE to be x86 specific

Rename ELF_MACHINE to be I386 specific. This is used as-is by the
multiboot loader.

Linux-user previously used this definition but will not anymore,
falling back to the default bahaviour of using ELF_ARCH as ELF_MACHINE.

This removes another architecture specific definition from the global
namespace.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Acked-By: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/multiboot.c

@@ -195,7 +195,7 @@ int load_multiboot(FWCfgState *fw_cfg,
         }
 
         kernel_size = load_elf(kernel_filename, NULL, NULL, &elf_entry,
-                               &elf_low, &elf_high, 0, ELF_MACHINE, 0);
+                               &elf_low, &elf_high, 0, I386_ELF_MACHINE, 0);
         if (kernel_size < 0) {
             fprintf(stderr, "Error while loading elf kernel\n");
             exit(1);

target-i386/cpu.h

@@ -37,10 +37,10 @@
 #define TARGET_HAS_PRECISE_SMC
 
 #ifdef TARGET_X86_64
-#define ELF_MACHINE     EM_X86_64
+#define I386_ELF_MACHINE  EM_X86_64
 #define ELF_MACHINE_UNAME "x86_64"
 #else
-#define ELF_MACHINE     EM_386
+#define I386_ELF_MACHINE  EM_386
 #define ELF_MACHINE_UNAME "i686"
 #endif